Numerous devices of this type are already known, the plate then having at least two recesses made in its thickness and passing right through it. They are spaced apart in such a way that they can be fitted respectively facing the two bits of bone. The recesses are designed to accept the fixing means of the aforementioned type. They generally comprise a ring or a collar, screw-fitted into the recess. The pin is then mounted through this collar which guides it in a set direction with respect to the plate, for example inclined at an appreciable angle with respect to a perpendicular to the plate. Document EP 1 583 478 for example discloses such a device and the pin is kept in a fixed position with respect to the plate by a locking sleeve in which the pin is engaged, and which is screwed into the collar, around the pin, along an axis that is angularly offset with respect to the axis of the pin. Thus, given this angular offset, the screwing of the locking sleeve gradually causes irreversible locking of the pin with respect to the plate.
That device works well when the pin extends in a direction substantially perpendicular to the plate or in a direction with a relatively small angular offset with respect to said perpendicular direction. By contrast, it is relatively awkward to keep in a fixed position a pin that is inclined through a plate. Furthermore, the pin has to be a precise fit in the locking sleeve which itself has to be fitted into the collar with extremely close tolerances. Hence, machining such parts requires special machine tools and, especially, relatively long manufacturing times with respect to the other mechanical parts of the same type. As a result, they are correspondingly more expensive.
So, one problem that arises and that the present invention aims to address is that of providing an osteosynthesis device which is able not only to hold a pin in a fixed position through a plate in directions that are inclined with respect to the plate, obviously very firmly, but which also is relatively cost-effective to produce.